ML20204H475
| ML20204H475 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 03/13/1987 |
| From: | Rubenstein L Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20204H480 | List: |
| References | |
| NUDOCS 8703270022 | |
| Download: ML20204H475 (4) | |
Text
t, 7590-01 UNITED STATES NUCLEAR REGIILATORY COMMISSION DUQUESNE LIGHT COMPANY, ET AL-BEAVER VALLEY UNIT 2 DOCKET NO. 50-412 NOTICE OF ENVIp0NMENTAL ASSESSMENT AND FINDING OF NO SIGNIFICANT IMPACT The U.S. Nuclear Regulatory Comission (the Comission) is considering issuance of a schedular exemption from a portion of the requirements of General Design Criterion (GDC) 4 (10 CFR 50, Appendix A) to the applicants
- for Beaver Valley Unit 2, located at Beaver County, Pennsylvania.
ENVIRONMENTAL ASSESSMENT:
Identification of Proposed Action: The schedular exemption would permit the applicants not to install the pipe whip restraints and iet impingement shields and not to consider the dynamic effects associated with postulated pipe breaks l
in certain Beaver Valley Unit 2 piping, on the basis of advanced calculat.ional methods (" leak-before-break") for assuring that piping stresses would not result in rapid piping failure. All of the affected piping are inside containment and include: reactor coolant loop bypass lines, safety injection lines, accumulator injection lines, pressurizer surge line, and residual heat removal i
lines.
Need for Proposed Action: The proposed exemption is needed in order for the applicants not to consider the dynamic loading effects associated with the postulated full-flow circumferential and longitudinal pipe ruptures in certain 2gQ{75$
e 2
- The applicants are Duquesne Light Company, Ohio Edison Company, the Cleveland Illuminating Company and the Toledo Edison Company.
piping. These dynamic loading effects include pipe whip, jet impingement, asymetric pressurization transients and break-associated dynamic transients 1
in unbroken portions of the subject piping. Therefore, the applicants would not be required to install protective devices such as pipe whip restraints and
.iet impingement shields related to postulated break locations for the subject-piping. Analysis shows that the pipe breaks, which these devices are designed to protect against, are extremely unlikely. On the other hand, the presence of these devices increase inservice inspection time in the containment and their elimination would lessen the occupational doses to workers and facilitate inservice inspections.
GDC 4 requires that structures, systems and components important to safety shall be appropriately protected against dynamic effects, including the effects of discharging fluids that may result from equipment failures.
In recent submittals, the applicants have provided information to show, by advanced fracture mechanics techniques, that the detection of small flaws by either inservice inspection or leakage monitoring systems is assured long before flaws i
in the piping materials can grow to critical or unstable sizes which could lead to large break areas. The NRC staff has reviewed and accepted the' applicants' conclusion and has published the results in Safety Evaluation Report Supplement No. 4 (NUREG-1057). The NRC staff agrees that double-ended guillotine break' in the piping so named above, need n'ot be required as a design-basis accident for l
pipe whip restraints. Accordingly, the NRC staff agrees that schedular exemption from GDC 4 is appropriate.
(The subject GDC 4 is currently being revised to pemit use of " leak-before-break" technology to preclude use o~f pipe whip restraints. The apoljcant's application is in line with the rulemaking but is ahead of it).
Environmental Trpact of the Proposed Action: The proposed exemption would not affect the environmental impact of the facility.
No credit is given for the restraints and shields to be eliminated in calculating accident doses to the environment. While the,iet impingement barriers and pipe whip restraints would minimize the damage from jet forces and whipping from a broken pipe, the calculated limitation on stresses required to support this exemption assures that the probability of pipe breaks which could give rise to such forces are extremely small; thus, the pipe whip restraints and jet shield would have no significant effect on the overall plant accident risk.
The exemption would not otherwise affect radiological plant effluents.
Likewise, the exemption would not affect non-radiological plant effluents, and has no other environmental impact. The elimination of the pipe whip restraints would tend to lessen the occupational doses to workers inside containment. Therefore, the Commission concludes that there are no significant radiological or non-radiological impacts associated with the exemption.
l The proposed exemption involves design features located entirely within the restricted area as defined in 10 CFR 20.
It does not affect plant non-radioactive effluents and has no other environmental impact. Therefore, the Commission concludes that there are no non-radiological impacts associated with this proposed exemption.
Since the staff has concluded that there are no measurable negative environmental impacts associated with this exemption, any alternatives would not provide any significant additional protection of the environment.
The alternative to the exemption would be to require literal compliance with GDC 4.
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- Alternative Use of Resources: This action does not ir.volve the use of resources not previously considered in the Final Environmental Statement (Operating Licensel for Beaver Valley Unit 2.
Aaencies and Persons Contacted: The NRC staff reviewed the applicants' request and applicable documents referenced therein that support this exemption for Beaver Valley Unit 2.
The NRC staff did not consult other agencies or persons.
FINDING OF NO SIGNIFICANT IMPACT The Commission has determined not to prepare an environmental impact statement for this action. Based upon the environr. ental assessment, the staff concludes that this action will not have a sionificant effect on the quality of the human environment.
For details with respect to this action, see the request for exemption dated February 2, 1987, as supplemented February 13, 1987. These documents, used in the NRC staff's technical evaluation of the exemption request, are available for public inspection at the Comission's Public Document Poom,
^
1717 H Street, N.W., Washington, D.C., and at the Local Public Document Room at the B. F. Jones Memorial Library, 663 Franklin Avenue, Aliouippa, Pennsylvania 15001. The staff's technical evaluation of the request has been published in Reaver Valley Unit 2 Safety Evaluation Report, Supplement 4 (NUREG-1057, Supplement 4) and is available for inspection at both locations listed above.
Dated at Bethesda, Maryland, this 13th day of March 1987.
FOR THE NUCLEAR REGULATORY COMMISSION Lester S.
ubenstein, Director PWR Pro.iect Directorate #2 Division of PWR Licensino-A l
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